First Spec Ideias

[jrmmendes]

Spec: V1

The project goal is to have a consistent service that wraps process.env, allowing users to validate if the environment has all required variables and apply any format validations.

The intended usage is something as follows:

1 - Create a function that implements the ValidationFunction interface:

type ValidationFunction<Environment> = (env: ProcessEnv, ...args: any[]) => Result<Environment>;

The Environment type refers to the expect environment variables. The validation process
must use the Result pattern to return either the reason for validation error, or the environment object with all values of process.env wrapped.

2 - Create the environment definition:

class MyEnvironment {
  @IsDefined()
  @IsIn(['DEV', 'HML', 'PRD'])
  NODE_ENV: string;
  
  @IsDefined()
  @isInt()
  PORT: number;
} 

Here I'm using something like class-validator, so we need to include those decorators to implement the validation function (althrough it would be a Joi schema or anything else);

3 - Use the ConfigurationServiceFactory to get a ConfigurationService instance:

import { ConfigurationServiceFactory } from '@mjsdevs/config.ts';

const service = ConfigurationServiceFactory
  .create<MyEnvironment>({
    validationFunction,
    env: process.env,
  });

4 - Get variables using the instance:

service.get('NODE_ENV');

// pass optional type paramenter to convert value in some desired format
service.get<number>('PORT');

[jrmmendes]

This is a simple working prove of concept, but it's coupled to class-validator and class-transformer
https://gist.github.com/jrmmendes/8db56c52ab79c57e30735501a3a7ffcc